Lewis acid-catalyzed [2π+2σ] cycloaddition of dihydropyridines with bicyclobutanes

-catalyzed cycloaddition of dihydropyridines with bicyclobutanes for the expedient synthesis of novel three-dimensional azacycle-fused bicyclo[2.1.1]hexane scaffolds. The reaction utilizes easily accessible starting materials and proceeds under mild, metal-free conditions with high atom efficiency.